In network computer systems, a plurality of client computers are typically connected together, and to one or more server computers in the network. A network may be established through the hard-wired interconnection of a plurality of computer terminals and servers in a local network, or on a wider scale such as an intranet, or the Internet or World Wide Web, which may include telecommunication links. In any case, the network server or servers act as the central control unit for providing access to files, programs, and program execution to the individual computers connected within the network.
With the increasing use of networks in general and multimedia presentations in particular, new opportunities are being developed for the design and delivery of data resources and assets in multimedia networks. In many applications, multimedia presentations are designed and created for delivery and presentation to both digital and analog display systems. For example, a user, or "client," on a network or on the Internet may select a particular video display segment or movie to be presented on the user's display device. The user may also create an "on-the-fly" presentation by selecting a series of "active" video display segments to be presented on the user's display device. Alternatively, a network administrator or manager may wish to assemble one or a series of "active" video segments on a server to be available to individual users on demand. In another application, a broadcast station may select and call for the presentation of one or a series of video segments for broadcast through associated stations to analog display devices of subscribers.
A client requests multimedia assets by communicating with a multimedia server. The component within the multimedia server which communicates with the client is sometimes referred to as an application server. If the application server fails, it is very disruptive to the client. If the failure occurs while a multimedia asset is playing, data may be lost, and the user may be unable to continue viewing the asset which was playing. Thus, in most multimedia systems, there is a high availability requirement for application servers.
Consequently, there is a need for a system and method for transferring control from one application server to another in a multimedia system. It would be desirable to allow a session to be taken over by a new application server, either by a request from the original application server, or after the original application server unexpectedly terminates. It would also be desirable if the session takeover could be accomplished without losing existing resources. It would be further desirable to be able to designate which sessions may be taken over.